Field of the Invention
The present invention relates to a non-contact power transmission apparatus using magnetism.
Description of the Related Art
A power storage apparatus has been known which converts electric power to kinetic energy of a rotating body (a flywheel, for example) and accumulates it and also converts the kinetic energy accumulated in the rotating body to electric energy and takes it out when necessary.
The power storage apparatus has a rotating body including a flywheel, a rotating shaft fixed to the flywheel, and a non-contact torque transmission component coupled to the rotating shaft arranged in an inner tank provided with a radiation shield tank and a vacuum container in the periphery thereof as illustrated in Patent Literature 1, for example. The rotating shaft of the rotating body is supported in a non-contact manner by a magnetic support device having a superconductor.
In the power storage apparatus constituted as above, the flywheel is placed in a high vacuum environment for conservation of energy and heat insulation, and the magnetic support device having the superconductor is used as a bearing of the rotating shaft so as to minimize friction resistance of the bearing.
In Non-Patent Literature 1, for example, there is described development of a freezer cooling type superconductive flywheel having a structure of supporting a large load in a non-contact manner by applying a superconductive magnetic bearing combining a superconductive coil and a superconductive bulk body to a flywheel. In the structure using the superconductive magnetic bearing for a flywheel, the superconductive coil is cooled to a critical temperature or below by conductive cooling using a refrigerating machine.
As a non-contact torque transmission component for transmitting power (rotary torque) to such flywheel, a magnetic coupling clutch device (hereinafter referred to as a “magnetic clutch”) is used which transmits a torque of a rotating shaft between an inside and an outside of a vacuum container formed of a non-magnetic plate as disclosed in Patent Literature 2, for example.
The magnetic clutch is a non-contact power transmission apparatus for transmitting power (rotary torque) in a non-contact manner between a driving shaft connected to a motor generator and a driven shaft. In general, the magnetic clutch includes a first clutch portion having a surface perpendicular to the driving shaft, provided with a permanent magnetic body or a coil (a copper wire, for example), and coupled to the driving shaft and a second clutch portion having a surface perpendicular to the driven shaft, provided with a permanent magnetic body generating a magnetic force between the first clutch portion and the second clutch portion, and coupled to the driven shaft. In the magnetic clutch, the first clutch portion and the second clutch portion face each other so that a gap portion is formed between the first clutch portion and the second clutch portion, and the non-magnetic plate of the vacuum container is interposed in the gap portion. That is, the first clutch portion is arranged outside the vacuum container, and the second clutch portion is arranged inside the vacuum container.
The first clutch portion and the second clutch portion attract each other by a magnetic force generated between the first clutch portion and the second clutch portion, and power on the driving side is transmitted to the driven side by rotation of the second clutch portion in conjunction with rotation of the first clutch portion.